Most cheap USB Type-C cables can't carry the full 3.0A required by the spec.

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One particularly conscientious Google engineer, Benson Leung, is currently on an unusual mission: he's slowly working his way through a bunch of USB Type-C cables and adaptors stocked by Amazon, to check whether they are actually up-to-spec and capable of charging his Chromebook Pixel.

First things first: of the ten USB Type-C products that Leung has reviewed, only three of them were fully specs-compliant and capable of charging his Pixel. The three good cables (Belkin, iOrange-E, Frieq) were invariably more expensive (about £15/$20) than the seven duff ones (£6/$10). Obviously there may be some cheap cables that do fulfil the full USB Type-C specification, but Leung hasn't found one yet.

Enlarge/ One of the offending micro-USB-to-Type-C adaptors that lacks the necessary hardware to comply with the Type C 1.1 spec.

The USB Type-C 1.1 specification allows for power delivery of up to 3A, which is enough juice to charge a laptop like the Chromebook Pixel. Previous USB specs, though, only allowed for power delivery of between 900mA and 1.5A. According to Leung, the problem is mostly related to how the cables deal with going from older Type-A or Micro/Mini connectors to the new Type-C connector.

I bought these two USB-C to Micro USB adapters from TechMatte and found they do not work properly with the Chromebook Pixel.

Upon closer inspection by our engineering team here, we have determined that this adapter is not correctly following the USB Type C specification...

Specifically, these adapters do not charge the Chromebook Pixel 2015 because the adapters leave the C-C lines floating, where the specification requires a Rp pullup to Vbus to identify the cable as a legacy adapter or cable... In other words, since you are creating a USB Type-C plug to a USB 2.0 Micro-B receptacle assembly, you must use a resistor of value 56kΩ as a pullup to Vbus. This cable does not do this.

In short, the cable doesn't fulfil the full Type-C 1.1 spec. Or, in Leung's own words, "If you are a consumer looking for a cable that is compatible with Pixel, do not use this one."

Further Reading

Most of Leung's reviews follow a similar pattern. In his review of the CableCreation Micro-to-Type-C adaptor, he calls them out for using a 10kΩ resistor instead of a 56kΩ. "By using this cable, your phone, tablet, or laptop computer may attempt to draw 3A, which may be more than the micro-b to A cable you attach to this adapter may be able to handle. This may cause damage to whatever cable, hub, pc, or charger you plug into this," Leung concludes.

If you take a broader look at the reviews on Amazon, it seems most of these cheaper cables still work when charging a smartphone—but using them to charge a higher-power device such as the Chromebook Pixel (and perhaps the new MacBook) probably won't work, and may be quite dangerous.

For the time being, until cheap third-party USB Type-C cables and adaptors become a little more mature, it's probably a good idea to stick to official products from Apple, Google, or products created by reputable third parties. If you're a Chromebook Pixel user, Leung has helpfully provided instructions on how you can check whether a Type-C cable/adaptor is up-to-spec.

For more information on the (somewhat confusing) Type-C connector, and how it dovetails into other standards such as USB 3.0 and USB Power Delivery, read our full explainer.

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Sebastian Anthony
Sebastian is the editor of Ars Technica UK. He usually writes about low-level hardware, software, and transport, but it is emerging science and the future of technology that really get him excited. Emailsebastian@arstechnica.co.uk//Twitter@mrseb

Except it's not groundless. In fact it sounds like he did a pretty thorough job reverse engineering exactly how they were building the cables and what they were doing wrong. Specs aren't wishy washy - if it's not spec compliant, it's not spec compliant. No if, ands, or buts.

Edit: I wish we could get more reviews like this for other cables/connectors. I know I'm always slightly leery when buying cables online. Like Cat 6/Cat 6a for instance.

Except it's not groundless. In fact it sounds like he did a pretty thorough job reverse engineering exactly how they were building the cables and what they were doing wrong. Specs aren't wishy washy - if it's not spec compliant, it's not spec compliant. No if, ands, or buts.

I think he was referring to these manufacturers trying to sue Leung for defamation, rather than the other way around. In which case, it would be groundless for the reasons you outlined.

Except it's not groundless. In fact it sounds like he did a pretty thorough job reverse engineering exactly how they were building the cables and what they were doing wrong. Specs aren't wishy washy - if it's not spec compliant, it's not spec compliant. No if, ands, or buts.

Edit: I wish we could get more reviews like this for other cables/connectors. I know I'm always slightly leery when buying cables online. Like Cat 6/Cat 6a for instance.

Ha, yeah, I was thinking the same thing. If only there were some vigilante cable testers who went around reverse engineering and electrically testing all of those various cheap cables on Amazon (and those audiophile/enthusiast cables too, I guess).

Except it's not groundless. In fact it sounds like he did a pretty thorough job reverse engineering exactly how they were building the cables and what they were doing wrong. Specs aren't wishy washy - if it's not spec compliant, it's not spec compliant. No if, ands, or buts.

Edit: I wish we could get more reviews like this for other cables/connectors. I know I'm always slightly leery when buying cables online. Like Cat 6/Cat 6a for instance.

Ha, yeah, I was thinking the same thing. If only there were some vigilante cable testers who went around reverse engineering and electrically testing all of those various cheap cables on Amazon (and those audiophile/enthusiast cables too, I guess).

I think the right answer is to buy the "made for iPhone" level cables as this guy has found.

Except it's not groundless. In fact it sounds like he did a pretty thorough job reverse engineering exactly how they were building the cables and what they were doing wrong. Specs aren't wishy washy - if it's not spec compliant, it's not spec compliant. No if, ands, or buts.

Edit: I wish we could get more reviews like this for other cables/connectors. I know I'm always slightly leery when buying cables online. Like Cat 6/Cat 6a for instance.

ChickenHawk is saying that the defamation lawsuit would be groundless (i.e. that the review is correct).

Except it's not groundless. In fact it sounds like he did a pretty thorough job reverse engineering exactly how they were building the cables and what they were doing wrong. Specs aren't wishy washy - if it's not spec compliant, it's not spec compliant. No if, ands, or buts.

Edit: I wish we could get more reviews like this for other cables/connectors. I know I'm always slightly leery when buying cables online. Like Cat 6/Cat 6a for instance.

ChickenHawk is saying that the defamation lawsuit would be groundless (i.e. that the review is correct).

I for one am glad someone is calling this stuff out. If its not to spec its not a good product to be bought. I need to be able to charge devices (cables for cell phones are absolutely horrible on this front) with breaking or they just stop charging after a few weeks use.

It's nice when a specialist takes the time to give informative reviews. Being a Linux user, I consider it a public obligation to mention in reviews how well a device works on Linux, or if I have to pull any tricks to get it to work.

This is one of the areas I learned where you can benefit from brand loyalty. Every time I have tried a cheap bargain brand for USB / charging peripherals, I have been disappointed.

I've had good luck with the stuff made by Anker- I would call them a "boutique" Chinese brand that specializes in peripherals and accessories. Their USB cables are sturdy and hold up well to abuse.

Except it's not groundless. In fact it sounds like he did a pretty thorough job reverse engineering exactly how they were building the cables and what they were doing wrong. Specs aren't wishy washy - if it's not spec compliant, it's not spec compliant. No if, ands, or buts.

Edit: I wish we could get more reviews like this for other cables/connectors. I know I'm always slightly leery when buying cables online. Like Cat 6/Cat 6a for instance.

ChickenHawk is saying that the defamation lawsuit would be groundless (i.e. that the review is correct).

Specs difficult for end users to verify are easy for manufacturers to lie about.

Amazon is replete with products that lied on their specs. It isn't just USB cables.

This is my experience as well. Amazon (especially the Marketplace) is pretty much an uncurated eBay-level hive of scum and villainy these days, at least for low cost commodity electronics like cables and chargers. Even if the cable is supposedly a name brand, don't rule out counterfeits.

So, has the output capability for USB host devices changed now, too? It thought USB has always been 5V, starting at 500mA, then went up to 1.5A. Looking at the pixel charger, it looks like it can output 5V 3A, 12V 3A, or 20V 3A (trickle/normal/fast charge, or device dependent voltage?). I am wondering if newer motherboards also output multiple voltages, or if they stick to the old common 5V USB?

Specs difficult for end users to verify are easy for manufacturers to lie about.

Amazon is replete with products that lied on their specs. It isn't just USB cables.

This is my experience as well. Amazon (especially the Marketplace) is pretty much an uncurated eBay-level hive of scum and villainy these days, at least for low cost commodity electronics like cables and chargers. Even if the cable is supposedly a name brand, don't rule out counterfeits.

Yes. On Amazon I've personally run across batteries that overstate their capacity by a factor of 4, solar panels that melt in the sun, flashlights that don't even come close to the stated lumens, lasers with wattages that aren't even possible, knockoff brand name electronics, knockoff Arduino and Raspberry PI parts, batteries with no thermal or short protection, battery chargers that simply output X voltage instead of following proper li-po charge procedures. It goes on and on and on.

Ugh. Is there a way to check the cables when using them on a smartphone? I picked up a handful of adapters from China when my wife got the Nexus 5X and I'd really like to avoid blowing anything up.

Yes, definitely. If you plug it in and it doesn't blow up then you should be OK. If it does blow up then you may want to consider that it is not OK.

LOL, that's about it---if all you have is a phone. The only way to test these properly is to first know the specs in minute detail, for example, enough that you can follow his quote in the article and understand every word and the implications of the various pull-up resistor values. ;-)

Second, you need some some good test equipment and the ability to take the devices apart and put probes on the components for measurements. No small feat, but I suspect many people here can do it.